Methods for processing red cell products for long term storage free of microorganisms

Abstract

A blood processing method provides a red blood cell product that is free of microorganisms like Yersinia enterocolitica during storage periods over 24 hours. The red blood cell product is collected in a first container, where it is refrigerating to cool the blood product to a temperature of about 3 to 5 degrees C. The refrigerated product is transferred from the first container into a storage container through a prescribed filter medium that comprises a mass of synthetic fibers having an average fiber diameter of about 10 microns or less and a bulk density of about 0.7 gram per cubic centimeter or less. The filtered product is retained in the storage container at a temperature of about 3 to 5 degrees C. for a storage period over 24 hours after filtration. Using the filter medium, microorganisms like Yersinia enterocolitica present in the red blood cell product at the time of collection are depleted. The filtered blood product remains free of clinically significant numbers of microorganisms throughout refrigerated storage up to time of transfusion.

We claim: 
     
       1. A method of processing a blood product containing red blood cells to remove microorganisms prior to long term storage, the method comprising the steps of: collecting the blood product containing red blood cells in a first container that forms a part of a sterile, closed blood collection system including a storage container, a first fluid path that leads into the storage container, the first fluid oath including a dry inline filter medium comprising a mass of synthetic fibers having an average fiber diameter of about 10 microns or less and a bulk density of about 0.7 gram per cubic centimeter or less, and a second fluid path that leads from the storage container to the first container and bypasses the filter medium,   adding a storage solution to the blood product without wetting the filter medium,   before conveying any of the blood product containing the storage solution from the first container into the storage container through the first fluid path and the filter medium, and before wetting the filter medium, refrigerating the blood product containing the storage solution in the first container together with the closed blood collection system to cool the blood product containing the storage solution and the dry inline filter medium to a temperature of about 3 to 5 degrees C., thereby creating a precooled blood product containing the storage solution and a precooled dry inline filter medium,   only after both the blood product containing the storage solution and the dry inline filter medium have been cooled to a temperature of about 3 to 5 degrees C., conveying the precooled blood product containing the storage solution from the first container into the storage container through the first fluid path and the precooled filter medium to remove microorganisms from the precooled blood product,   venting air from the storage container into the first container through the second fluid path that bypasses the filter medium, and   after venting the air from the storage container, storing the filtered, microorganism-depleted blood product containing the storage solution in the storage container at a temperature of about 3 to 5 degrees C. for a period that exceeds twenty-four hours after filtration.   
     
     
       2. A method according to claim 1 and further including the step of transfusing the filtered, microorganism-depleted blood product at the end of the storage period.